Geotechnical Engineering Design of a Tunnel Support System - A Case Study of Bheri Babai Headrace Tunnel

摘要

The analysis of rock mass strength, geological problem related to tunnel construction and designing appropriate support system for Bheri Babai Headrace Tunnel (BBDMP) is presented in the paper. Tunnel squeezing and rock burst is checked before design of support system. Rock mass classification system (Q and RMR) are used as empirical method to obtain recommended support system. For analytical solution Convergent confinement method is used to determine required support pressure to resist displacement. Finite element modelling using Phase 2 version 7.013 is used to check the ground condition and stress concentration around the tunnel providing support systemfor resisting the deformation. The displacement and radius of plastic zone is reduced after installation of support shown by obtained results. The first two method i.e. empirical and analytical provide first estimate to design while numerical method can be used to verify the performance of support system. Hence design method providing maximum factor of safety should is recommended.